Seminar: Dr. Sergey Korkin | UMBC/ Gestar-II

ABSTRACT: The seminar advertises our series of, so far, three papers explaining the process of writing codes for simulation of multiple scattering [1], line-by-line [2], and continuum [3] absorption of monochromatic sunlight in a plane-parallel Earth’s atmosphere over a reflecting surface. Numerical simulation of these physical processes, commonly called radiative transfer (RT) in physics and forward modeling in remote sensing (RS), is one of the three pillars of RS, together with measurement and inversion.

The goal of the series is to efficiently share our RT skills with experts from relevant fields as well as newcomers. We expect little experience in RT from the readers, while the result is guaranteed (as references to our papers confirm) by:

This “from zero to hero” philosophy distinguishes our effort from old-fashioned papers (packed with sophisticated equations) and from RT codes that are often more powerful than ours (but not always easy to understand or support). In order to put the discussion into context, I will also talk about standard RT techniques, limited to those I have used for about 20 years during and after my PhD.

[1] Korkin S., Sayer A.M., Ibrahim A., and Lyapustin A., A Practical Guide to Writing a Radiative Transfer Code, Computer Physics Communication, 271: 108198, 2022.

[2] Korkin S., Sayer A.M., Ibrahim A., and Lyapustin A., A Practical Guide to Coding Line-by-line Trace Gas Absorption in Earth's Atmosphere, Journal of Quantitative Spectroscopy and Radiative Transfer, 337: 109345, 2025.

[3] Korkin S., Sayer A.M., Ibrahim A., and Lyapustin A., A Practical Guide to Simulating Continuum Absorption in the in Earth's Atmosphere, Journal of Quantitative Spectroscopy and Radiative Transfer, submitted for review: 02/2026.

Bio:  In 2009, Sergey Korkin received a PhD in Electro-Optical Systems, with a focus on Radiative Transfer (RT), from Moscow Power Engineering Institute (Moscow, Russia). In 2010, he joined NASA Goddard Space Flight Center (GSFC) as a contractor first with UMBC, then with USRA (2011-2021), and now with UMBC again. He has used his vector (polarized) matrix-operator RT code IPOL (Intensity and POLarization) [1], in different incarnations - first in Matlab, later in Fortran, now in C/C++ - to account for polarization of multiple scattering of sunlight in look-up table (LUT)-based Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm [2] (PI: Dr. Alexei Lyapustin, GSFC). IPOL.F90 contributed to the creation of accurate benchmarks for polarized RT in a plane-parallel atmosphere over different surfaces: land and ocean [3]. In 2014-2017, Dr. Korkin served as a Principal Investigator (PI) on a NASA-funded proposal “Fast Polarized RT Code for V3 AERONET Reprocessing”. A new polarized successive orders of scattering code SORD, also in Fortran, was created [4] and built into the AERONET retrieval algorithm [5]. Dr. Korkin shares his experience in RT codes development by publishing “A practical guide to writing a radiative transfer code” (in Python) [6] and “A practical guide to coding line-by-line trace gas absorption in Earth’s atmosphere” (in C/C++) [7]. Throughout his career, Dr. Korkin has published over 50 papers, including 16 as first author, focusing on

different aspects of RT.

[1] https://doi.org/10.1016/j.jqsrt.2023.108663

[2] https://doi.org/10.5194/amt-11-5741-2018

[3] https://doi.org/10.1016/j.jqsrt.2015.05.007

[4] https://doi.org/10.1016/j.jqsrt.2017.04.035

[5] https://doi.org/10.5194/amt-13-3375-2020

[6] https://doi.org/10.1016/j.cpc.2021.108198

[7] https://doi.org/10.1016/j.jqsrt.2025.109345